Introducing the Democratic Electoral Systems data, 1919-1945

This data note introduces an update to the widely-used Democratic Electoral Systems (DES) data that encompasses the period from 1919 to 1945. The data include 243 legislative lower house and presidential elections in 34 interwar democracies. Information on these elections falls into four categories: first and foremost, DES contains variables that capture the institutional rules that define how elections are organized. Second, the data captures the consequences of electoral rules in the form of summary statistics of electoral outcomes. Third, we include democracy classifications for four major democracy datasets so that users can choose their preferred democracy definition when working with the data. Finally, the DES dataset contains multiple identification variables that allow linking the DES data to a wide variety of other datasets. This update to the DES data is fully compatible with prior releases for the post-war period 1– 3 .


Introduction
We are introducing an update to the widely-used Democratic Electoral Systems (DES) data that encompasses the period from 1919 to 1945.The data include 243 legislative and presidential elections in 34 interwar democracies.Information on these elections falls into four categories: first and foremost, the DES data contains variables that capture the institutional rules that define how elections are organized.Second, the data captures the consequences of electoral rules in the form of summary statistics of electoral outcomes.Third, we include democracy classifications for four major democracy datasets so that users can easily choose their preferred democracy definition when working with the data.Finally, the DES dataset contains multiple identification variables that allow linking the DES data to a wide variety of other datasets.
In addition to a new variable on the constitutionally prescribed length of time between elections, this release of the historical DES data contains all variables of prior releases for the postwar period, and is thus fully compatible with them [1][2][3] .These DES versions have been used to analyse a broad range of questions in political science, economics, sociology, and related disciplines.Most recently, social scientists employed the data to explore outcomes such as affective polarization 4 , voting preferences in general 5 , for left and right-wing parties in particular 6 , and public participation in policy-making 7 .Prior versions of the data on electoral rules entered analyses of party systems 8 , party breakdown 9 , foreign direct investment 10 , ethnic coalitions 11 , the development of legislatures in Africa 12 , and elite reactions to far right challengers 13 .All these studies are highly pertinent to studying the future of democracy. 1though this release of the DES data covers a historical period, studies of the tumultuous interwar years might be able to teach us something about the fate of democracies today 14 .Studying electoral choices and reforms during the interwar period can inform debates about contemporary institutional changes.Historical party systems are relevant comparison cases for studies of the effects of party fragmentation today 15,16 .Finally, the DES 1919-1945 release will prove a valuable resource for scholars who study the origins of electoral systems, for example, to explore the diffusion of electoral rules across Europe and the Americas 17 .
In the following, we describe how we collected the data, how we ensure data quality, and provide a range of summary statistics that describe the data.

Materials & methods
The DES data assembles and harmonizes previously scattered and analogue sources into one data set 18 .Whenever possible, we rely on primary sources, such as official election returns from statistical or government agencies, and electoral laws.Edited volumes that unite case studies on electoral systems and electoral returns constitute crucial secondary sources [19][20][21][22] .We cross-referenced different sources to ensure data validity.When sources disagreed, we provide the information given by a majority of sources or contacted country experts.
Data collection relies on the experiences made in three previous rounds of post-World War II DES releases [1][2][3] and proceeded in six steps: 1. We defined the sample of elections to be included in the data.All elections must be democratic according to one of four major democracy indices: the dichotomous measure by Boix, Miller & Rosato 23 , the dichotomous Democracy and Dictatorship (DD) classification 24,25 , the ordinal Polity5 index 26 , and the continuous Varieties of Democracy (V-Dem) Polyarchy scale 27 .Since the original DD classification only starts in 1946, we classified all elections in the data according to its rules.
2. We trained student research assistants (RAs) on the coding rules of the DES data 1,3 .The training involved a theoretical overview of electoral rules, the introduction of relevant source material, and example classifications of two elections.
3. Each RA classified the same set of ten randomly selected elections.We compared RA classifications to our own classification of these elections, and provided individual performance feedback to each RA.
4. We divided the election sample between RAs according to linguistic expertise.Between ourselves and the RAs, we were able to read source material in Dutch, English, Finnish, French, German, Italian, Serbo-Croatian, Spanish, and Swedish.In total, we spoke the languages used in 26 out of the 34 countries included in the dataset.For the remaining eight countries, we relied on secondary sources or contacted country experts.We encouraged RAs to contact us with questions when they were uncertain how to classify a particular variable or election.When our reading of sources could not provide an answer to unclear cases, we contacted other leading experts on electoral systems and/or particular countries to help us reach a decision.

Amendments from Version 1
We made two major changes in response to reviewer requests.First, we added a global map that depicts the global distribution of electoral families (majoritarian, proportional, mixed) in the first election in our sample (Figure 4).Second, we collected a new variable that records the constitutionally prescribed inter-election times, so that users now how many elections are typical for a country.Finally, we clarified minor issues throughout the text.
Any further responses from the reviewers can be found at the end of the article REVISED 5. We randomly re-sampled about 10% of elections and reclassified them to see if systematic errors occurred, and corrected them where necessary.
6. Specific variables are automatically created.For example, we compute the effective number of electoral parties (ENEP) at each election through an algorithm that summarises election results into the overall index.For most elections, we link DES elections to electoral results collected by the authors in a different dataset, the Actions by Elites and Leaders (ABEL) data 16 .For all other elections, we collected raw electoral results from the sources described above.
7. In a final step, we ran an automated script across the entire data to check each variable for its consistency with the coding rules, which identifies typos and other data entry mistakes.The script also ensures inter-variable consistency and thereby guarantees that two variable values do not contradict each other.For example, if the variable legislative_type indicates the use of proportional representation (PR) in a particular election, we checked that the variables elecrule and tier1_formula indicate specific PR sub-types but not sub-types of any other electoral family.
The dataset comes with several identification variables that make it interoperational with other scientific and public-use datasets.Most users of the DES data are likely to link it to other country-level datasets.Thus, next to a unique variable that identifies each election (elec_id), the dataset provides several country-identifiers, including the country name, the country abbreviation, the Alvarez, Limongi, Cheibug & Przeworski country codes (aclp_code) 24 along with the widely-used Correlates of War (COW) country codes (ccode) 28 and the Gleditsch & Ward (GW) country IDs (ccode2) 29 .Unlike identification systems of country names and different ISO country abbreviations, the COW and GW identification variables accurately trace the historical development of the international system. 2

Democratic Electoral Systems, 1919-1945
To The former consider all but two Spanish parliamentary elections in 1919 and 1920 as democratic 23 .DD neither classifies the two Spanish elections as democratic, nor three elections in San Marino 24 . 3The more complex V-Dem and Polity5 indices categorize 185 and 173 elections respectively as democratic.Users of our data thus have the choice to pick their preferred definition of democracy and the associated sample of elections, or to take an inclusive approach by picking all elections that have been classified as democratic by at least one democracy indicator.In the following, we present descriptive statistics for all election recognized as democratic by at least one of the four democracy indicators.
Our data includes information on 213 legislative, lower-house and 30 presidential elections in 34 democracies between January 1st, 1919 and December 31st, 1945.Figure 1 shows the distribution of regime types across the globe.26 states featured a parliamentary regime (light grey), two a semi-presidential form of government (black), and four were presidential (dark grey). 4Geographically, the majority of democratic states were situated in Europe (25), while the rest clustered in Latin America and the Caribbean ( 5), in North America (2), and in the Pacific (2). 5 Figure 2 depicts the frequency of legislative and presidential elections per decade. 6The declining number of elections tracks the breakdown of democracy in many European states.Notably, the steeper decline in legislative compared to presidential elections contrasts with the greater instability of presidential systems in the post-World War II period 30 .This observation raises theoretical questions regarding the stability of presidential versus parliamentary systems, which we would not be able to investigate further without data from the interwar period.
To enable users to compare the frequency of elections between different democracies, we added a new variable that describes the constitutionally prescribed duration in years between legislative and presidential elections.For example, members of the United States' House of Representatives run for office every two years, while parliamentarians in interwar Czechoslovakia only faced voters every six years.We record the 2 The two slightly differ in how they identify ancestor and successor states.For example, the COW system sees unified Germany after 1990 as a successor to Imperial/Nazi Germany before 1945, whereas GW classify unified Germany as a successor of West Germany.R R 3 Both BMR and DD do not consider the Spanish elections as democratic because the unelected Spanish monarch could dismiss governments and revoke laws.The DD rules further dismiss the San Marino elections because the country did not experience an alternation in executive power in the period 1906-1922. 4Parliamentary regimes feature no popular presidential elections.In semipresidential regimes, the president is head of state but not head of the government.In presidential regimes, the president is both, head of state and head of government.Only Ireland changed its democratic regime type from parliamentary to semi-presidential when adopting a new constitution in 1937.longest electoral cycle in our data for presidential elections in Germany, which took place every seven years.Moreover, we also collected information on the partial renewal of parliament.For example, lower house elections in Argentina take place every two years for 50% of MPs.These on term lengths do not only allow users to compare another characteristic of electoral rules but also facilitate weighting the number of units per country in cross-country quantitative comparisons.We publish them in a separate data sheet to ease merging the interwar data with its post-World War II counterparts.

Legislative elections
Most of the information in the DES data focuses on legislative elections.The included variables provide different classifications of electoral families, electoral rules, their application and combination within or across different levels of aggregation or electoral tiers, the number and average size of districts, and the resulting number of parties at each election.Figure 3 displays the distribution of legislative electoral families per decade.During the interwar period, electoral rules that translate votes proportionally into seats were roughly twice as common as majoritarian systems which award seats to the candidate(s) with the highest vote total(s) in a district.Combinations of proportional and majoritarian rules, so-called mixed systems, were uncommon during the interwar period, and only used in France and Iceland.
Figure 4 shows that list PR systems were the most popular proportional rule with the D'Hondt divisor as the most common way to allocate votes into seats (49\% of all PR elections).
Geographically, all Anglo-Saxon states ran their elections under majoritarian rules as Figure 4 shows.Spain, during its first democratic spell in the early 1920s, also operated a first-past-the-post system.The other two majoritarian states, Argentina and Portugal, used the limited vote---an electoral system with multi-member districts, in which voters have fewer votes than there are seats.Besides the majoritarian United Kingdom and France, all other European countries had adopted PR in the early 1920s.Among the PR states, only Ireland departed from the list-PR consensus, and used the Single Transferable Vote (STV) instead.France was the only continental European state that held two of its five elections under mixed electoral rules.The only other mixed electoral system in our sample was employed in Iceland.During the interwar period, the country was part of a union with Denmark and not yet internationally recognized, which is why it is not depicted in Figure 4. Its voters elected four MPs by D'Hondt in the Reijkjavik constituency in addition to 12 seats in six two-member districts and 20 seats in single-member constituencies by plurality.In the 1919 and 1924 elections, France employed a mixed fusion system in multi-member districts.
Voters had as many votes as there were seats in a given district (Borda Count) and candidates were elected if they received more votes than there were voters in a given district.
Candidates were also part of lists.In a second stage, list votes were distributed by the Hare formula.If turnout in a constituency was lower than 50% or if no list passed the electoral quota a second round was to take place 14 days later in which a relative majority of votes was sufficient.
Two democracies used electoral systems that have not been used by any other state in national elections during the time period covered by any previous DES data release (1946-2020), and thus enter the DES data for the first time.Germany used the fixed quota system that distributed one seat for 60,000 votes 31,[73][74][75][76][77][78][79][80][81] .Unlike most quota systems, which fix the number of parliamentary seats and determine the quota after counting the votes, the fixed quota system reverts this relationship.It sets the quota first and then determines the number of parliamentary seats.This practise led to an ever larger parliament as Germany's population and electoral participation grew.The size of the German Reichstag swelled from 459 deputies in 1920 to 647 members after the final election in March 1933.The second unique system, the cumulative vote, was employed in Chile until 1921 32 .It is similar in all but one respect to the majoritarian block vote system, in which voters have as many votes as there are seats in multi-member districts.However, voters can award more than one vote to a candidate under the cumulative vote.
Next to detailed information on legislative electoral rules, the DES data also provide insight into the consequences of these rules in the form of party system size figures.presents box plots of the effective number of electoral (enep) and parliamentary parties (enpp) across electoral families (top) and within familes over time (bottom). 7In line with theoretical predictions 33 , majoritarian systems are associated with the smallest number of parties while PR systems are most permissive.From 1920 to 1940, the effective number of parties in PR systems decreases more steeply than in majoritarian systems (bottom panels).In part, this may be a selection effect where countries with more parties where more likely to fail.For example, four of the five democracies with the highest (enep) scores failed in the interwar period. 8esidential elections Presidential elections constitute just over 12% of all elections in the DES, 1919-1945 data.As shown in Figure 1 presidential regimes clustered in the Americas.European democracies were overwhelmingly of parliamentary types with semi-presidential exceptions in Finland, Germany, and Ireland after 1937.
This low share contrasts markedly with the post-World War II period, when more than a quarter of all elections were presidential 1,3 .
Mirroring the early post-World War II decades, the electoral college was the most common electoral system used in presidential elections during the interwar period, closely followed by plurality elections (see Figure 6).Absolute majority systems and the alternative vote, that was only used in Ireland, were employed in less than 20% of all presidential elections.
Finally, we do not find any notable association between presidential electoral rules and the number of candidates.
Whereas plurality systems are associated with a smaller and less variable number of presidential candidates relative to absolute majority systems in the 20th and 21st centuries 3,34,35 , we find virtually no differences between electoral rules in the period 1919-1945.This null finding may in part be explained by the small number of elections observed during the period that does not result in sufficient variation.Another factor could be the relatively young age of interwar democracies.Out of ten states that held presidential elections, only the United States had been a democracy for more than a decade before 1919, when our dataset starts recording elections.
Candidates and voters might have had too little time to learn about the mechanical and strategic effects of electoral rules.This difference in the associations between different features of electoral systems for periods before and after 1945 is of theoretical relevance.We want to encourage researchers to explorer these differences further.

Conclusion
In this data note, we described an update to the Democratic Electoral Systems (DES) data that extends the coverage to the period 1919-1945.Recently, concerns about the quality and survival of contemporary European and other long-established democracies are on the rise.Our new data can help answer questions about the association of parliamentary and presidential institutions as well as party system fragmentation on one hand, and the fate of democracies in another troubled period on the other.The DES 1919-1945 data might also be of use to scholars interested in the origins of electoral rules or long-term institutional legacies.
recent addition to the Democratic Electoral Systems around the world data.As the authors pointed out it encompasses the period from 1919 to 1945 and consists of 243 legislative lower house and presidential elections in 34 interwar democracies.The structure of the article is standard, consisting of an introduction, a description of the materials and methods, a substantial part, and a conclusion.The introduction is well structured and determines the framework and focus of the article.The methodology is described step-by-step, it is relevant for the goal of the study and is reproducible.The inclusion of regime types along with the electoral systems (and their sub-types) provides more options for analysis.The application of different conceptual frameworks to define democracy is another benefit for the users.
Substantially, the new addition to the DES dataset has a wide range of benefits for scholars and for all interested in the elections.The historical background is rather significant in the explanation of the contemporary state in a given national context, tracing the origins of transformations.Of particular importance is the collection of information for a historical period, which enables researchers to expand the range of analyses.Thanks to the addition to the database, it is now possible to compare the period before and after the Second World War, institutional transformations (in particular electoral legislation), and changes in societies.It is possible to examine the dynamics in a country's electoral rules from 1919 to the present by relating them to the dynamics in society.Alongside, associations between the structure of parliaments determined by the electoral rules and the decisions of states regarding the Second World War events might be identified.The above-mentioned are only part of the huge potential that the new database provides.In summary, current challenges cannot be fully understood without knowledge of the historical context, and DES 1919-1945 provides this opportunity to have accessible data on processes regarding the elections in contemporary democracies.
The submitted article can be indexed as is, both structurally and substantively.However, concerning the DES, I would like to make a suggestion.Some of the countries that do not appear in the database are democracies nowadays.It seems to me that following the evolution of their electoral rules would contribute to a better understanding of the processes of democratization.Thus, if DES can be supplemented with more European countries although if not defined as democratic in the examined period, it will have a greater contribution to the comparative politics.

Is the rationale for creating the dataset(s) clearly described? Yes
Are the protocols appropriate and is the work technically sound?Yes

Are sufficient details of methods and materials provided to allow replication by others? Yes
Are the datasets clearly presented in a useable and accessible format?Yes Competing Interests: No competing interests were disclosed.
Reviewer Expertise: Elections and electoral systems, comparative politics, political culture

Pedro Riera
University Carlos III of Madrid, Madrid, Spain This is a much-needed article (dataset) on electoral systems in democratic countries in the interwar period.The authors have managed to compile an immense quantity of reliable and useful data that I expect to be widely employed by comparativists of all over the world in the coming years.For this main reason, I support indexing of the article.Having said that, I am listing in the next paragraphs a battery of ideas that, in my view, could improve the dataset and the resulting article.
My main concern about the article is that electoral systems per se should play a bigger role in it.Let me offer a couple of examples: Figure 1 displays information on regime types across the world.However, a similar graph with information on electoral system in use in each country does not exist.Electoral systems are the main object of the article and, as such, they should occupy a more prominent position when offering descriptive information. 1.
The article starts by very briefly explaining the main elements of the new dataset (i.e., electoral rules, consequences of electoral rules, democracy indices and ID variables).However, I was missing some extra focus on the electoral rules variables.Which ones are included in the article?One can imagine that these are going to be the same that appear in the "sequel", the widely acclaimed Bormann et al.'s "Democratic Electoral Systems around the world, 1946-2020" dataset, but this needs to be explicitly said.On top of that, I have always considered the omission of an "electoral thresholds" 2. 1.
variable in the original dataset as one its main mistakes.The reader wonders if this is also the case here and, if so, why the authors have not included information on this important element of democratic electoral systems.Elections as unit of analysis.In the previous Electoral Studies articles, the authors use as unit of analysis the election rather than the country.This sometimes can result misleading because the number of elections a country holds depends, among others, on the constitutional inter-election period.In order to be sure that the latter is not entirely responsible for this effect, I suggest that the authors include a new variable in the dataset that captures the duration of the constitutional inter-election period.

Dubious theoretical claims:
In page 5, the article argues that the steeper decline of the number of elections in PR countries is due to the geographical clustering of these countries in Europe rather than the type of system of government in place in these countries.However, the reader wonders how the geographical clustering of parliamentary systems in Europe can lead to this result.What is the (theoretical) mechanism linking these two variables (that is, geography and democratic survival)?I am aware of several ideas in this regard, the existence of domino/diffusion effects being the most prominent ones, but these points need to be made clearer in the article. 1.
In page 9, when talking about the effects of formulas in presidential elections, the authors allude to the "relatively young age of many democracies" to justify the existence of null effects in this regard.However, these effects do exist when examining the role of formulas in legislative elections (see previous pages).How can it be this discrepancy whether democracies are of relatively the same age?2.

3.
Small points (page 6): When talking about how uncommon mixed systems were in the interwar period, provide examples (for example, Denmark).

1.
Why not including a figure about frequency of types of PR electoral formulas?2.

Are the datasets clearly presented in a useable and accessible format? Yes
Competing Interests: No competing interests were disclosed.
Reviewer Expertise: Comparative politics, electoral systems, voting behaviour.
I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard, however I have significant reservations, as outlined above.
analyzed are not spoken by the research assistants may limit the reliability of the findings.Second, in which respect the DES dataset improves the understanding of the diffusion of electoral rules across Europe and the Americas is unclear.Historically, most of the colonized countries adopted the electoral systems of their imperial rulers.It remains to be seen whether such kind of diffusion can be mentioned for democracies as well.Third, additional information on how many elections are classified as "democratic" based on this reductionist account of the "democracy-dictatorship" classification would be beneficial.As widely noted, a binary classification overlooks the increasing prevalence of regimes that fall between these extremes.Finally, I am not fully convinced whether using the sub-title "democratic electoral systems" is conceptually appropriate.If we mention "democratic electoral systems," then are there also "authoritarian" electoral systems or even "totalitarian" ones?How do they look like?Imagine an electoral authoritarian regime with little or no ethnic and religious pluralism.If this country adopts an electoral system that maximizes descriptive representation of the society, can we call the electoral system "democratic"?
Is the rationale for creating the dataset(s) clearly described?Yes

Are the datasets clearly presented in a useable and accessible format? Yes
Competing Interests: No competing interests were disclosed.
Reviewer Expertise: comparative politics I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard.

R 1 Overall
, the the dataset has been cited 1439 times according to a Google Scholar query on 26 August 2023.
accommodate different views of democracy, we identify democratic elections according to four different democracy definitions.Each election in the DES 1919-1945 has been classified as democratic by at least one of four datasets.Two inclusive classifications identify almost all 243 elections in the dataset as democratic.Boix, Miller & Rosato's (BMR) Complete Data of Political Regimes and Pzeworski et al.'s Democracy and Dictatorship (DD) data.

Figure 1 .
Figure 1.Regime types across the world.First election per country depicted.

Figure 4 .
Figure 4. Legislative types across the world.First election per country depicted.